Additive manufacturing as a key technology for sustainable hydrogen production

In the last blog post, my colleague Wejdane Ezzine talked about the importance of hydrogen production for the energy transition and showed the added value that ceramic 3D printing offers in the electrolysis of green hydrogen.

If you haven’t read the article yet, you can find it here: Blog post: New ways to produce hydrogen – Wejdane Ezzine

Around 95% of global hydrogen production is currently based on the steam reforming of methane (CH₄). In this process, methane – the main component of natural gas – is converted into hydrogen (H₂) and carbon dioxide (CO₂) with the addition of water vapor.

The problem:
This process produces considerable CO₂ emissions. Each kilogram of hydrogen produced generates around 9 kg of CO₂. In total, global hydrogen production causes around 830 million tons of CO₂ every year.

Methane pyrolysis as a sustainable alternative

Methane pyrolysis is a promising alternative to conventional steam reforming.

Hydrogen is also obtained from methane in this process. In contrast to steam reforming, however, no oxygen is added. This produces solid carbon in the form of soot instead of CO₂.

If the process is also operated with renewable energy sources or biogas, methane pyrolysis can make an important contribution to a sustainable energy supply.

Advantages of methane pyrolysis

Compared to steam reforming, the technology offers several decisive advantages:

• No direct CO₂ emissions
• Production of high-purity hydrogen
• Extraction of stable carbon as an industrially usable by-product
• Potential for a significantly better carbon footprint

SUPSI develops 3D-printed reactors made of graphite

The Swiss research institute SUPSI is investigating the use of additively manufactured gyroid structures made of graphite as reactor components for methane pyrolysis.

The reactors are used to split methane into hydrogen and solid carbon.

Why is graphite a suitable material?

Graphite, or synthetic carbon, has a number of extraordinary material properties:

• High thermal conductivity
• High electrical conductivity
• Excellent temperature resistance
• High chemical resistance
• Very good mechanical stability

This makes the material ideal for high-temperature processes such as methane pyrolysis.

Why are gyroid structures suitable for reactors?

Additive manufacturing enables the production of complex geometries that are almost impossible to realize with conventional manufacturing processes. These include so-called gyroid structures.

These have a sponge-like, continuously curved geometry and offer ideal conditions for use in reactors.

Advantages of gyroid structures

• Extremely high surface area per volume
• Continuous curved surfaces
• No abrupt edges or dead spaces
• Optimized flow conditions
• Improved heat transfer

This can significantly increase the efficiency of the reactor. More electrochemical reactions can be realized with the same volume.

This means: higher hydrogen yield or more compact systems with the same output.

Results of the SUPSI studies

SUPSI was able to successfully equip the graphite reactors with the InnoventX system from Desktop Metal system.

The investigations showed that the 3D-printed reactors can improve the efficiency of methane pyrolysis. In particular, the heat requirement for splitting methane into hydrogen and carbon could be reduced.

According to the researchers, SUPSI is one of the first institutes in the world to have published scientific papers on additively manufactured graphite structures.

Challenge: The processing of graphite

A particular challenge when processing graphite is that the material cannot be melted.

This means that graphite is not suitable for laser-based 3D printing processes such as laser powder bed fusion. Binder jetting offers decisive advantages here.

SUPSI developed on the open InnoventX system first developed the appropriate printing parameters for producing a stable green body. Two important post-processing steps were then carried out to achieve the final material properties.

Step 1: Precursor infiltration

After printing, the graphite components still have numerous pores and cavities. These are reduced by what is known as precursor infiltration.

A carbon-rich precursor material – in this case a furan resin – is introduced into the pore structure.

The liquid resin penetrates deep into the open structures.

Targets of the infiltration

• Reduction of porosity
• Increasing the material density
• Improvement in mechanical strength
• Optimization of thermal and electrical properties

Step 2: Pyrolysis

In the second step, the infiltrated component is heated to a high temperature in the absence of oxygen.

This causes the furan resin to decompose thermally:

• Volatile components escape as gas
• what remains is solid carbon

This gives the component its final properties and the necessary stability for use in the reactor.

Scaling through large-volume binder jetting systems

The industrial scaling of reactor production is carried out using large-volume binder jetting platforms, such as the X160 Pro system from Desktop Metal.

Thanks to the large construction volume, even complex and large-sized reactor components can be manufactured economically.

Conclusion: Binder jetting opens up new potential for hydrogen production

Methane pyrolysis is considered a promising technology for more climate-friendly hydrogen production. Especially in combination with renewable energies, the process offers great potential to significantly reduce CO₂ emissions compared to conventional steam reforming.

At the same time, the SUPSI project demonstrates the contribution that additive manufacturing can make to the further development of such processes. Binder jetting can be used to create highly complex reactor geometries from graphite that would be almost impossible to implement using conventional manufacturing processes. The investigations also show that binder jetting goes far beyond traditional metal applications. Technical ceramics and carbon-based materials are increasingly becoming a strategically relevant field of application for additive manufacturing – especially for applications in energy, process and environmental technology.

Interested?

Would you like to find out more about binder jetting?
Then please contact us – we will be happy to advise you personally.

Frederik Nussbaumer
Head of Sales
+49 172 4059105
frederik.nussbaumer@am-pioneers.com