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EP-4739619-A1 - METHOD FOR PRODUCING HYDROGEN AND MAGNETITE FROM WATER AND IRON

EP4739619A1EP 4739619 A1EP4739619 A1EP 4739619A1EP-4739619-A1

Abstract

The present invention relates to a method for producing hydrogen and magnetite from water and iron in the presence of an iron(II) salt catalyst. The invention also relates to the use of the iron obtained as an indirect hydrogen store.

Inventors

  • KÖHNE, Stephan-Hans, Dr.
  • Konrad, Martin, Dr.

Assignees

  • KS IPR UG

Dates

Publication Date
20260513
Application Date
20240612

Claims (10)

  1. 1. Process for producing hydrogen and magnetite from water and iron, wherein the water is brought into contact with the iron as a liquid in the presence of at least one catalyst, characterized in that a) the at least one catalyst is selected from iron(II) chloride, iron(II) sulfate, iron(II) nitrate, iron(II) phosphate or iron(II) acetate; b) the process is carried out at a temperature of 60 to 400 °C, and c) the process is carried out at a pressure at which the water is predominantly present as a liquid.
  2. 2. Process according to claim 1, characterized in that the catalyst is used in an amount of 1 - 100 mol%, preferably 5 - 100 mol%, based on the limiting reagent.
  3. 3. Process according to at least one of claims 1 to 2, characterized in that the process is carried out at a higher pressure and corresponding temperature, in particular at a pressure below 221 bar and at a temperature of up to 373 °C, so that the water remains liquid.
  4. 4. Process according to at least one of claims 1 to 3, characterized in that it further comprises the following step: d) separating magnetite and hydrogen from the reaction solution at the end of the reaction.
  5. 5. Process according to at least one of claims 1 to 4, characterized in that the magnetite and the catalyst are separated from each other so that the catalyst can be used again in a process according to at least one of claims 1 to 4.
  6. 6. Process according to claim 5, characterized in that the separation of magnetite and the catalyst is carried out by means of a magnet, washing and/or filtering.
  7. 7. Process according to at least one of claims 1 to 6, characterized in that at least one further catalyst selected from a metal oxide, in particular titanium oxide, is used.
  8. 8. Process according to claim 1, characterized in that the process is carried out without oxygen, preferably under inert gas.
  9. 9. Process according to at least one of claims 1 to 8, characterized in that the process is carried out at a temperature of 90 - 190 °C.
  10. 10. Process according to at least one of claims 1 to 9, characterized in that the iron obtained is used as an indirect hydrogen storage medium.

Description

PROCESS FOR THE PRODUCTION OF HYDROGEN AND MAGNETITE FROM WATER AND IRON The present invention relates to a process for producing hydrogen and magnetite from water and iron, whereby the water reacts with the iron in the presence of a catalyst. The iron used can be obtained beforehand, for example, by reducing the resulting magnetite or other compounds. Hydrogen is seen as the energy source of the future. It is a flexible and easily transportable energy source. Hydrogen can be produced using water electrolysis, among other methods. The energy required for this is very high and storage is energy-intensive. For example, hydrogen is cooled to -253 °C under very high pressure for better storage. This has the advantage that the gas becomes liquid and can therefore be transported in a more space-saving manner. However, this compression costs a lot of energy. The steam iron reaction for producing hydrogen has been known for more than 100 years and was used industrially until the early 1970s. The steam iron reaction is usually carried out in the range of 500 °C at atmospheric pressure. For this, water is evaporated and the reaction therefore also takes place in the gas phase. As a result, the energy efficiency is low due to the necessary water evaporation and the reaction or process requires high safety standards due to the gas phase. Furthermore, it is well known that it is possible to produce hydrogen using iron and an acid. However, per hydrogen produced For every equivalent of hydrogen, one equivalent of iron and two equivalents of acids are required. Since this is a very uneconomical method of producing hydrogen and produces stoichiometric waste, this process is not normally used outside of the laboratory scale. Due to the problems and disadvantages of the current state of the art, as well as the problems related to fossil fuels and climate change, there is a great need to provide a new process that provides a safe, energy-efficient method for producing hydrogen from iron. There is also a need for a sensible energy storage system to transport hydrogen easily and efficiently in the future. Surprisingly, it has been shown that hydrogen can be extracted from liquid water using iron in combination with an iron(II) salt catalyst. By using liquid water, safety risks are minimized and less energy is required to evaporate the water. In addition, the hydrogen extracted can be used for iron reduction and the iron recovered in this way can be reused in another process to generate hydrogen. The process thus offers a new possibility for long-term indirect hydrogen storage using extracted iron. This means that hydrogen can be transported and stored more energy efficiently and safely. In a first embodiment, the object underlying the present invention is therefore achieved by producing hydrogen and magnetite from water and iron, wherein the water is brought into contact with the iron as a liquid in the presence of at least one catalyst, characterized in that a) the at least one catalyst is selected from iron(II) chloride, iron(II) sulfate, iron(II) nitrate, iron(II) phosphate or iron(II) acetate; b) the process is carried out at a temperature of 60 to 400 °C, and c) the process is carried out at a pressure at which the water is predominantly present as a liquid. According to the invention, iron and water are brought into contact in the presence of an iron(II) catalyst selected from iron(II) chloride, iron(II) sulfate, iron(II) nitrate, iron(II) phosphate or iron(II) acetate, in particular at a temperature of 90-190°C. Furthermore, the pressure in the process is selected according to the invention such that the water is predominantly present as a liquid. This means according to the invention that a gas phase, which also contains water in vapor form, can be present above the liquid phase in a reactor in which the reaction takes place. According to the invention, however, the iron only reacts with the water in the liquid phase. According to the invention, it is also unimportant which component is initially introduced and which is added. Iron and water react with one another in an aqueous solution, with iron being oxidized to iron oxide or magnetite. Hydrogen is formed. According to the invention, predominantly as a liquid means that the water is present at least 85% by weight, particularly at least 90% by weight and in particular at least 95% by weight in the liquid phase based on the total amount of water. The process according to the invention thus provides a new, energy-efficient way of producing hydrogen. The hydrogen can then be collected and used directly as a raw material or as an energy source. In a preferred embodiment, the magnetite produced can be reacted again with hydrogen in a subsequent process, which in turn produces iron. The iron serves as an indirect energy source for the hydrogen because it can be used again and again to produce hydrogen using the process according to the invention. This aspect solves the p