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A group from Queen Mary University of London (QMUL), together with the companies Cambridge Carbon Capture (CCC), Modern Age Plastics​ (MAPI) and researchers/collaborators at Sapienza University of Rome, McMaster University and the University of British Columbia worked with ISIS science and engineering staff to develop a new piece of equipment for testing a process that not only permanently captures carbon dioxide but turns it into a greener ingredient for making concrete.

Transforming carbon dioxide (CO₂) into something useful would be hugely beneficial for helping balance global carbon emissions. Known as carbon capture & utilisation (CCU), this process offers a means to utilise carbon, as well as permanently storing it in solid form. One example is mineral carbonation that makes carbon containing minerals such as calcium and magnesium carbonates, which comprise over 4% of the Earth's crust.

The carbonation process involves dissolving CO₂ in water, in the same way that sparkling water is made and then combining it with a source of calcium, sodium or magnesium to form carbonates. Carbonated materials are in high demand, as they can be used in infrastructure and beyond, with revenues expected to reach $1 trillion/yr by 2030, according to the Utilization Panel Report: CO₂ Conversion to Solid Carbonates.

First generation CO₂ mineralisation reactor for in-situ tracking of CO₂-utilisation in real-time.

​Magnesium carbonate is more profitable and of wide industrial use, with sources of magnesium existing in large quantities worldwide, such as in seawater and magnesium silicate containing rocks. These contain sufficient magnesium to mitigate all human-based carbon emissions for the next 1000 years. Magnesium carbonates can also be used as a filler aggregate for making concrete and, under optimal conditions, can replace some of the cement powder used. This is especially beneficial as the global cement industry is a very large contributor to atmospheric carbon: if it were a country, its emissions would place it third in the world behind the USA and China.

However, magnesium carbonates are also more challenging to form. When trying to optimise CO₂-mineralisation, it is important to know what is happening in real-time at the nanoscale during the process, and this is what the research team came to ISIS to do. Neutrons are ideal for this study, as their interaction with different elements mean that all components of the system, even the water, can be studied for their influence on the carbonate minerals produced.

Neutrons are also highly penetrating, which meant the team could build a mock-up of the industrial setup without having to worry about the neutrons being blocked by the walls of the reaction vessel during the measurements. In addition, the relatively large quantity of sample required for neutron studies was actually beneficial, as it more closely mimicked industrial conditions and took the experiment one step closer to industrial scales.

In collaboration with ISIS scientists, the ISIS design office and engineering teams, the company Cambridge Carbon Capture and research collaborators at Sapienza University of Rome, the team from QMUL were able to successfully design and build a prototype industrial CO₂-mineralisation reactor for use on neutron beamlines at ISIS.

This allowed the team to replicate industrial conditions of the mineral-carbonation reactions and to watch and study the material during the mineralisation process in real time. “We were insistent on retaining relevance, including real-world impure starting materials and conditions that are like the ones in real-world settings and not at all well-behaved!", said Dr Gregory Chass from QMUL.

“Although these conditions presented a challenge to generate manageable data, we were after relative trends to inform industrial processes.", added Dr Kun Viviana Tian from Sapienza University.

The reactors were used for measurement on the Vesuvio and Iris beamlines at ISIS in May and July 2021, respectively, overcoming not only scientific challenges but also those associated with Covid-19 restrictions. Throughout the design and build stages, as well as during measurements at ISIS, collaboration was achieved through online video calls, allowing the entire team at ISIS, QMUL, CCC and in Italy and Canada to be linked in real-time across seven time zones​​. A true sign of the times.

“We learned a lot about what we could do to improve all aspects," said Dr Devis Di Tommaso from QMUL. “This provided the opportunity for us to evolve our designs and implement them in the next generation of reactors we are building for the next measurements at ISIS."

Their experiments showed that the rig was a success: for the first time, they were able to measure time-resolved neutron spectra of the mineralisation of carbon dioxide to magnesium carbonates and resolve general trends and patterns to the inform the industrial processes.

“Like home-baked cakes, they're different for every oven, yet as long as its not too hot to burn the outside or too cold stopping it from rising, its generally OK. Its finding those 'just right' conditions for each 'oven' that industry are after for the bulk processes and in widely varied locations.", concluded Dr. Gregory Chass (QMUL).

Further information:

The full publication can be found at DOI: 10.1063/5.0136204​

Other relevant references relating to the project and CO₂-mineralisation:

• Boggs, Sam (2006). Principles of sedimentology and stratigraphy (4th ed.). Upper Saddle River, N.J.: Pearson Prentice Hall. pp. 177, 181. ISBN 0-13-154728-3.
• Blatt, Harvey; Tracy, Robert J. (1996). Petrology: igneous, sedimentary, and metamorphic (2nd ed.). New York: W.H. Freeman. pp. 295–300. ISBN 0-7167-2438-3.
• Mission Innovation, Accelerating Breakthrough Innovation in Carbon Capture, Utilization, and Storage, Houston, Texas, 2017.
• The Growing Role of Minerals and Metals for a Low Carbon Future, World Bank Group (2017).
• M. S. Imbabi, C.Carrigan, and S, McKenna, Int. J. Sustain. Built Environ. 1, 194 (2012).
• Carbonate industry @ $1 trillion/yr by 2030:  Mission Innovation, Accelerating Breakthrough Innovation in Carbon Capture, Utilization, and Storage, Houston, Texas, 2017, Page 3-19
• ISIS Staff directly involved: Ali Mortazavi, Michael Dudman, Franze Demmel and Stewart Parker