Hydrogen production from biomass waste at low temperature

Abstract

Converting biomass waste into hydrogen gas has great potential in sustainable energy production. This invention provides a low-temperature catalytic process that efficiently converts biomass waste into high-purity hydrogen gas using MgO catalyst and palladium / nitrogen-doped carbon catalyst. This innovative method can reduce energy costs, avoid the production of solid residues, and help promote a circular economy. This technology is suitable for different types of biomass waste and provides a scalable solution for clean hydrogen production.

Description

Cross-reference to related applications

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 558,656, filed February 28, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] This invention relates to the fields of hydrogen production, renewable energy and waste management, and specifically to the production of hydrogen from biomass waste using an innovative low-temperature catalytic process. Background Technology

[0003] Hydrogen is a clean and versatile energy carrier with various applications in fuel cells, transportation, and industrial production. Traditional hydrogen production methods, such as methane steam reforming and electrolysis, have significant drawbacks, including high energy consumption, large carbon emissions, and reliance on fossil fuels.

[0004] In recent years, the use of biomass waste as a renewable and sustainable feedstock for hydrogen production has received increasing attention. Several existing inventions have explored hydrogen production from biomass waste. However, these inventions still face certain limitations and challenges.

[0005] One common problem with existing inventions is the need for high-temperature processes, which typically require expensive and energy-intensive equipment. This limits the feasibility and large-scale application of hydrogen production from biomass waste.

[0006] Therefore, there is a need for an improved technology capable of producing hydrogen from biomass waste at low temperatures. This technology can address the challenges faced by existing inventions and provide a more efficient, cost-effective, and environmentally friendly method for hydrogen production. This invention aims to solve the aforementioned challenges. Summary of the Invention

[0007] This invention aims to provide an integrated and efficient conversion pathway that optimizes the process by using a specific catalyst and uses the resulting high-purity hydrogen for clean energy applications, thereby demonstrating novelty and inventiveness in advancing sustainable energy solutions.

[0008] In a first aspect, the present invention provides a catalytic method for producing hydrogen from biomass waste under low-temperature conditions. The method comprises: treating the biomass waste with an acid of a concentration of 0.01-0.5 M to generate soluble carbohydrates; oxidizing the soluble carbohydrates (using an oxidant such as H₂O₂, oxygen, or O₃) to one or more organic acids using an active catalyst; and dehydrogenating the organic acids using a palladium / nitrogen-doped carbon catalyst to produce hydrogen. The method achieves a hydrogen production rate of at least 50%, and the method is carried out at a temperature below 200°C without producing solid residues.

[0009] In one embodiment, the acid includes sulfuric acid, hydrochloric acid, nitric acid, phosphate, formic acid, acetic acid, or combinations thereof.

[0010] In one embodiment, the active catalyst includes magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide, and precious metals such as palladium, platinum, gold, ruthenium, rhodium, and silver.

[0011] In another embodiment, the active catalyst is in the form of a nanostructure, including nanoflowers or nanoparticles, to increase the surface area and improve catalytic efficiency.

[0012] Preferably, the active catalyst is magnesium oxide nanoflowers, and the magnesium oxide nanoflowers are prepared by a hydrothermal method, which includes: dissolving magnesium chloride and urea in deionized water at a ratio of 1:0.5 to 1:5 to obtain a solution; adjusting the pH of the solution to about 9 using ammonia; subjecting the solution to hydrothermal treatment in an autoclave to obtain a product; and calcining the product at 400-500°C for 2-5 hours to obtain the magnesium oxide nanoflowers.

[0013] In one embodiment, the hydrothermal treatment is carried out at a temperature of 120°C to 250°C for 0.5 to 3 hours.

[0014] In one embodiment, the palladium / nitrogen-doped carbon catalyst is prepared by the following steps: calcining a mixture of chitosan and potassium carbonate under a nitrogen atmosphere to prepare nitrogen-doped carbon; dispersing the nitrogen-doped carbon in water and impregnating it with palladium nitrate to achieve a palladium loading of 0.1-10 wt%; and reducing the palladium nitrate with sodium borohydride, followed by washing and drying to obtain the palladium / nitrogen-doped carbon catalyst.

[0015] In one embodiment, the biomass waste includes agricultural residues, forestry residues, municipal solid waste, energy crops, algae, aquatic plants, wood waste, or food waste.

[0016] In one embodiment, the resulting organic acid is further subjected to a selective hydrogenation reaction.

[0017] In one embodiment, the purity of the produced hydrogen gas is at least 70%, and can reach 99% simply by passing it through an alkaline solution (e.g., NaOH solution, Ca(OH)2 solution).

[0018] In one embodiment, the yield of hydrogen produced from the biomass waste is from 125 mL / g to 175 mL / g.

[0019] In another embodiment, the method further includes recycling the active catalyst at least 10 times without significant loss of catalytic activity.

[0020] In another aspect, the present invention provides a system for producing hydrogen from biomass waste. The system includes: a reactor configured to treat the biomass waste with acid to generate soluble carbohydrates; an oxidation unit for converting the soluble carbohydrates into organic acids; and a dehydrogenation unit for producing hydrogen. The system operates at a low temperature below 200°C and produces no solid residue.

[0021] In one embodiment, the system further includes a heat recovery unit for utilizing the heat generated during the catalytic process to improve energy efficiency.

[0022] In one embodiment, the dehydrogenation unit operates at a temperature of 50°C to 150°C.

[0023] This invention relates to a technology for producing hydrogen from biomass waste at low temperatures. Specifically, it relates to a method and system for efficiently converting biomass waste into hydrogen through a low-temperature process. This invention covers the utilization of various types of biomass waste, including but not limited to agricultural residues, forestry residues, and municipal solid waste. By employing an innovative method, this technology aims to address the challenges of high energy consumption and environmental problems faced by traditional hydrogen production methods. This invention provides a sustainable and environmentally friendly hydrogen production scheme, and the produced hydrogen can be used as a clean energy source in various applications, including fuel cells and industrial processes.

[0024] The material preparation and hydrogen production processes required by this invention do not require harsh conditions such as high temperature or high pressure. Furthermore, these processes have undergone rigorous optimization and testing, making them highly suitable for large-scale industrial applications. Attached Figure Description

[0025] Embodiments of the invention are described in more detail below with reference to the accompanying drawings, in which:

[0026] Figure 1 A block diagram showing the bread waste-glucose-formic acid process is shown.

[0027] Figure 2 A schematic diagram of a hydrogen production process from bread waste is shown. Detailed Implementation

[0028] In the following description, methods and systems for cryogenic catalytic hydrogen production from biomass waste are illustrated as preferred examples. It will be apparent to those skilled in the art that modifications, including additions and / or substitutions, can be made without departing from the scope and spirit of the invention. Specific details may be omitted to avoid obscuring the invention; however, this disclosure is intended to enable those skilled in the art to practice the teachings herein without excessive experimentation.

[0029] Clean and efficient hydrogen energy is an alternative energy source to fossil fuels. Developing green hydrogen production pathways is of great significance. Therefore, this invention provides a series of sequential catalytic reactions for in-situ hydrogen production from biomass waste. By employing a series of catalytic steps, high hydrogen yields can be achieved while reducing byproduct generation and energy consumption.

[0030] Specifically, the process involves treating biomass waste with acid to generate soluble carbohydrates, oxidizing the soluble carbohydrates to organic acids using an active catalyst, and then dehydrogenating the organic acids to produce hydrogen.

[0031] Reference Figure 1 In the acid hydrolysis step, the biomass waste is treated with an acid of concentration 0.1-0.5 M to generate soluble carbohydrates. The treated bread waste is acid-hydrolyzed using sulfuric acid to obtain an aqueous solution containing a high concentration of soluble carbohydrates.

[0032] After soluble carbohydrates are generated from the biomass, a further oxidation process is performed. In this oxidation step, an active catalyst is used to catalytically oxidize the dissolved carbohydrates to efficiently prepare an aqueous solution of organic acids. The active catalyst is selected to effectively promote the conversion of soluble carbohydrates to organic acids under low-temperature conditions, typically below 200°C. Subsequently, the soluble carbohydrates are oxidized to one or more organic acids.

[0033] After the soluble carbohydrates are oxidized to organic acids, the next step is to dehydrogenate the organic acids to produce hydrogen. In the dehydrogenation step, the heterogeneous magnesium oxide catalyst is readily separated from the system and subsequently replaced with a palladium / nitrogen-doped carbon catalyst for in-situ dehydrogenation of the aqueous organic acid solution. The palladium / nitrogen-doped carbon catalyst plays a key role in promoting the release of hydrogen from the organic acid under relatively mild conditions.

[0034] In one embodiment, the present invention is capable of processing various types of biomass waste, including agricultural residues (e.g., corn stalks, rice husks), forestry residues (e.g., wood chips, sawdust), municipal solid waste, energy crops (e.g., switchgrass, miscanthus), algae, aquatic plants, wood waste, or food waste. The wide range of biomass material sources makes the system applicable to various industries and regions dealing with different types of waste.

[0035] In one embodiment, the present invention employs different active catalysts at each stage to ensure a high hydrogen conversion rate and reduce the formation of byproducts. The hydrogen conversion rate is calculated using the following formula:

[0036] The highly efficient catalyst may include magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide, and precious metals such as palladium (Pd), platinum (Pt), gold (Au), ruthenium (Ru), rhodium (Rh), and silver (Ag).

[0037] In one embodiment, the concentration of the acid used can be from 0.01 M to 0.5 M, wherein the acid is typically an inorganic or organic acid, such as sulfuric acid, hydrochloric acid, nitric acid, or other suitable acid. The choice of acid depends on the specific characteristics of the biomass and the efficiency required to produce soluble carbohydrates.

[0038] In some cases, the organic acids produced may include acetic acid, formic acid, lactic acid, or other similar organic acids formed during carbohydrate oxidation.

[0039] In one embodiment, the active catalyst may be in the form of nanoflowers, or in other forms as needed. For example, the magnesium oxide nanoflowers are prepared by a hydrothermal method.

[0040] In one embodiment, the palladium / nitrogen-doped carbon catalyst is synthesized using a nitrogen-doped carbon support impregnated with palladium nitrate and reduced with sodium borohydride. The palladium / nitrogen-doped carbon catalyst is supported on a high specific surface area material, such as activated carbon, silica, or alumina, to improve its catalytic performance and stability during the dehydrogenation reaction. The palladium / nitrogen-doped carbon catalyst is used in a continuous flow reactor for the continuous production of hydrogen from biomass waste.

[0041] Optionally, the palladium / nitrogen-doped carbon catalyst may be further doped with other metal or non-metal elements to improve its catalytic activity and stability during the dehydrogenation reaction.

[0042] In one embodiment, the method of the present invention is carried out at a low temperature below 200°C and produces no solid residue. This significantly reduces energy consumption compared to conventional pyrolysis processes that typically require temperatures of 700°C or even higher, making the hydrogen production process more cost-effective. The produced hydrogen has a high purity (at least 70%), making it suitable for direct use in fuel cells and other applications.

[0043] For example, the method of the present invention can be carried out at temperatures below 150°C, below 100°C, or below 50°C, or at room temperature.

[0044] By optimizing the dehydrogenation reaction time by controlling the temperature and pressure in the reaction vessel, the hydrogen yield can be increased while reducing side reactions.

[0045] In contrast, conventional technologies typically employ single-step processes using fewer or no catalysts, resulting in lower efficiency and increased byproduct formation.

[0046] This invention employs advanced technology to optimize the conversion process, reducing emissions and maximizing energy recovery, thereby balancing environmental sustainability and economic feasibility. The biomass material can be converted into valuable byproducts such as biofuels, biochemicals, and other renewable energy sources. Unlike other technologies that produce solid biochar residues, this process generates no solid waste, thus providing a cleaner and more sustainable solution.

[0047] The novel method can be carried out at low temperatures, thus eliminating the need for the high temperature and high pressure conditions typically required by traditional hydrogen production methods.

[0048] Furthermore, this invention is scalable and can be tailored to the specific needs of small, medium, or large-scale operations, making it a universal solution applicable to waste-to-energy applications worldwide.

[0049] Example

[0050] Example 1

[0051] Preparation of magnesium oxide nanoflowers

[0052] 0.04 mol of magnesium chloride (MgCl2) and urea were dissolved in deionized water at a ratio of 1:0 to 1:5, and an appropriate amount of a metal salt, such as lithium chloride (LiCl), calcium chloride (CaCl2), or cerium chloride (CeCl3), was added to the solution. The amount of the metal salt could be adjusted according to the desired catalytic performance (the molar ratio of metal to Mg could be 0-5%), and the pH was adjusted to approximately 9 using ammonia. The mixture was then transferred to a PTFE-lined autoclave and hydrothermally treated in an oven at 110-180°C for 2-24 hours. After cooling, the resulting white powder was collected, separated by centrifugation, and washed three times. Finally, the resulting solid was dried in an oven at 60°C and then calcined at 450°C for 4 hours.

[0053] Example 2

[0054] Preparation of palladium / nitrogen-doped carbon catalysts

[0055] Chitosan and potassium carbonate (K₂CO₃, >99.9%) were mixed at a weight ratio of 1:0.5 to 1:10 and ground until free of particles. The mixture was placed in a tube furnace and calcined at 700°C for 5 hours under a nitrogen atmosphere (heating rate of 5°C / min). The calcined product was washed and dried to obtain a nitrogen-doped carbon support. Subsequently, 200 mg of the C / N support was dispersed in an appropriate amount of Milli-Q water. A calculated amount of palladium nitrate (Pd(NO₃)₂, >99.9%) solution was added to the above solution to achieve a palladium loading of 9.2%. The resulting mixture was stirred at 500 rpm for 30 minutes. Subsequently, 2 mL of a 0.85 M sodium borohydride (NaBH₄, >99.9%) solution was added, and the mixture was stirred for 1 hour. The resulting solid product was centrifuged and washed, and then dried in an oven at 60°C to remove moisture to obtain a palladium / nitrogen-doped carbon catalyst. The catalyst preparation method described above can be extended to a variety of noble metal catalysts (e.g., Au, Ru, Rh, Ag, Co, Cu, Ni). The preparation method is similar to that of palladium / nitrogen-doped carbon catalysts. For example, gold catalysts can be prepared using HAuCl4, platinum catalysts using H2PtCl6, rhodium catalysts using RhCl3, silver catalysts using AgNO3, cobalt catalysts using Co(NO3)2, copper catalysts using Cu(NO3)2, or nickel catalysts using Ni(NO3)2.

[0056] Example 3

[0057] A process for producing hydrogen from breadcrumbs using a catalytic step.

[0058] First, 1 g of dried and ground breadcrumbs was added to a high-pressure reactor along with 45 mL of sulfuric acid solution (H₂SO₄, 0.1 M) and stirred at a constant speed for 2 hours at 120°C. The resulting crude solution was neutralized with 1 M sodium hydroxide (NaOH), and then the same oxidation steps were performed. Typically, 120 mg of MgO catalyst was added to the above solution, and a 30% aqueous solution of H₂O₂ was placed in a transparent glass reactor (25 mL) with a plastic lid. The sealed reactor was then immersed in a water bath at 323 K. After reacting for 4 hours, the product solution was separated from the heterogeneous MgO catalyst by centrifugation. The separated solid catalyst was washed three times and dried overnight, then calcined at 773 K for use in the next reaction. The reaction solution was acidified with 0.5 M sulfuric acid, and then dehydrogenation was carried out without any additives. After removing the heterogeneous MgO catalyst, a palladium / nitrogen-doped carbon catalyst was added to the above solution, and the hydrogen production reaction was carried out at 323 K.

[0059] Reference Figure 2 The graph shows the volume of hydrogen (H2) produced over time. The horizontal axis represents time (minutes), and the vertical axis represents the volume of hydrogen produced (milliliters). The hydrogen volume increases rapidly in the first 2 minutes, then the rate of increase slows down, and stabilizes at approximately 6.5 mL after about 3 minutes. The total hydrogen production measured was 6.5 mL. This indicates a relatively fast reaction rate initially, followed by a stabilization as the reaction likely completes. Table 1 lists the hydrogen yields from various biomass wastes. This efficient and sustainable hydrogen production process provides a new approach for green hydrogen production using food waste and biomass waste.

[0060] Table 1 Waste types Hydrogen yield (mL / g) Bread waste 172.33 Corn waste 145.47 Potato waste 139.50 Rice waste 152.93 Wheat waste 167.10 sugarcane waste 125.33 *The operation steps are similar to those described above, while the hydrogen yield of the traditional pyrolysis method is 71-87 mL / g.

[0061] The foregoing description of the invention has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to those skilled in the art.

[0062] The embodiments have been selected and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention with respect to the various embodiments and with various modifications suitable for the intended particular application.

[0063] definition

[0064] Throughout this specification, unless the context otherwise requires, the word “comprise” or variations such as “comprises” or “comprising” should be understood to imply inclusion of the stated whole or group of wholes, but not to exclude any other whole or group of wholes. It should also be noted that in this disclosure and particularly in the claims and / or paragraphs, terms such as “comprises,” “comprised,” and “comprising” may have the meaning attributed to them under U.S. patent law, for example, allowing for elements not expressly listed but excluding elements present in the prior art or affecting the essential or novel characteristics of the invention.

[0065] Furthermore, throughout this specification and claims, unless the context otherwise requires, the word "include" or variations such as "includes" or "including" shall be understood to imply inclusion of the stated whole or group of wholes, but not to exclude any other whole or group of wholes.

[0066] References to "an embodiment," "an example embodiment," "exemplary embodiment," etc., in this specification indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes that particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is believed that the influence of such feature, structure, or characteristic on other embodiments is within the knowledge of those skilled in the art, whether explicitly described or not.

[0067] As used herein, the terms “approximately,” “substantially,” “basically,” and “about” are used to describe and explain small variations. When used in conjunction with an event or situation, the terms can refer to the exact occurrence of the event or situation, or approximately the occurrence of the event or situation. As used herein with respect to a given value or range, the term “approximately” generally refers to a range of ±10%, ±5%, ±1%, or ±0.5% of the given value or range. Ranges described herein can be expressed as from one endpoint to another or between two endpoints. Unless otherwise stated, all ranges disclosed in this disclosure include endpoints. When referring to the same value or characteristic “substantially,” the term can refer to a value within ±10%, ±5%, ±1%, or ±0.5% of the average of the values.

[0068] In the preparation methods described herein, steps may be performed in any order without departing from the principles of the invention, except where the timing or order of operations is explicitly stated. A statement in a claim that implies performing a step first, followed by several other steps, should be interpreted as meaning that the first step is performed before any of the other steps, but the other steps may be performed in any suitable order unless the order is further stated in the other steps. For example, a claim element stating "steps A, B, C, D, and E" should be interpreted as meaning that step A is performed first, and step E is performed last, and steps B, C, and D may be performed in any order between steps A and E, and such order still falls within the literal scope of the claimed process. A given step or subset of steps may also be repeated. Furthermore, unless the steps specified in the explicit claim language are performed separately, the specified steps may be performed in parallel.

[0069] The term "acid" refers to an acid that can dissociate in water to produce hydrogen ions (H+). + Any inorganic or organic compound containing a proton or a proton.

[0070] The term "soluble carbohydrates" refers to carbohydrates that can dissolve in water to form an aqueous solution, including but not limited to sugars such as glucose, fructose, and sucrose, as well as water-soluble oligosaccharides and polysaccharides.

[0071] The term "active catalyst" refers to a substance that can accelerate the oxidation of soluble carbohydrates into one or more organic acids without being consumed in the reaction.

[0072] The term "organic acid" refers to any carbonic acid that can be produced by oxidizing soluble carbohydrates.

[0073] The term "palladium / nitrogen-doped carbon catalyst" refers to a catalyst containing palladium (Pd) supported on nitrogen-doped carbon (CN), wherein the nitrogen doping in the carbon structure is intended to improve the catalytic activity and stability of palladium in the hydrogen production process.

[0074] The term "magnesium oxide nanoflower" refers to magnesium oxide nanostructures that exhibit a flower-like morphology and typically possess high specific surface area and unique structural features.

[0075] The term "hydrogen purity" refers to the proportion of hydrogen (H2) in a gas mixture, excluding other gases or contaminants. The purity is expressed as a percentage of hydrogen relative to the total volume of gases produced in the reaction.

[0076] Other definitions of the selected terms used herein can be found in the specific description of the invention and apply throughout. Unless otherwise defined, all other technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

Claims

1. A catalytic method for producing hydrogen from biomass waste under low-temperature conditions, characterized in that, The method includes: The biomass waste is treated with an acid of 0.01-0.5 M to generate soluble carbohydrates; The soluble carbohydrates are oxidized to one or more organic acids using an active catalyst; and The organic acid was dehydrogenated using a palladium / nitrogen-doped carbon catalyst to produce hydrogen. The method achieves a hydrogen production rate of at least 50%, and is carried out at a temperature below 200°C without producing organic solid residues.

2. The catalytic method according to claim 1, wherein the acid comprises sulfuric acid, hydrochloric acid, nitric acid, phosphate, formic acid, acetic acid, or a combination thereof.

3. The catalytic method according to claim 1, wherein the active catalyst comprises magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide, and noble metals including palladium, platinum, gold, ruthenium, rhodium, and silver.

4. The catalytic method according to claim 3, wherein the active catalyst is in the form of a nanostructure, including nanoflowers or nanoparticles, to increase the surface area and improve the catalytic efficiency.

5. The catalytic method according to claim 4, wherein the active catalyst is magnesium oxide nanoflowers, and the magnesium oxide nanoflowers are prepared by a hydrothermal method, the hydrothermal method comprising: Magnesium chloride and urea are dissolved in deionized water in a ratio of 1:0.5 to 1:5 to obtain a solution; The pH of the solution was adjusted to approximately 9 using ammonia. The solution is subjected to hydrothermal treatment in an autoclave to obtain the product; as well as The product was calcined at 400-500°C for 2-5 hours to obtain the magnesium oxide nanoflowers.

6. The catalytic method according to claim 5, wherein the hydrothermal treatment is performed at a temperature of 120°C to 250°C for 0.5-3 hours.

7. The catalytic method according to claim 1, wherein the palladium / nitrogen-doped carbon catalyst is prepared by the following steps: A mixture of chitosan and potassium carbonate was calcined under a nitrogen atmosphere to prepare nitrogen-doped carbon. The nitrogen-doped carbon was dispersed in water and impregnated with palladium nitrate to achieve a palladium loading of 0.1-10 wt%; and The palladium nitrate was reduced using sodium borohydride, followed by washing and drying to obtain the palladium / nitrogen-doped carbon catalyst.

8. The catalytic method according to claim 1, wherein the biomass waste includes agricultural residues, forestry residues, municipal solid waste, energy crops, algae, aquatic plants, wood waste, or food waste.

9. The catalytic method according to claim 1, wherein the resulting organic acid is further subjected to a selective hydrogenation reaction.

10. The catalytic method according to claim 1, wherein the purity of the produced hydrogen is at least 70%, and can reach 99% after passing through an alkaline solution alone.

11. The catalytic method according to claim 10, wherein the alkaline solution comprises NaOH solution or Ca(OH)2 solution.

12. The catalytic method according to claim 1, wherein the yield of hydrogen produced from the biomass waste is from 125 mL / g to 175 mL / g.

13. The catalytic method according to claim 1, wherein the method further comprises recycling the active catalyst at least 10 times without significant loss of catalytic activity.

14. A system for producing hydrogen from biomass waste, characterized in that the system comprises: A reactor configured to treat biomass waste with acid to produce soluble carbohydrates; An oxidation unit for converting the soluble carbohydrates into organic acids; And a dehydrogenation unit for producing hydrogen, wherein the system operates at a low temperature below 200°C and produces no solid residue.

15. The system of claim 14, wherein the system further comprises a heat recovery unit for utilizing the heat generated during the catalytic process to improve energy efficiency.

16. The system of claim 14, wherein the dehydrogenation unit operates at a temperature of 50°C to 150°C.

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