CO2 from the flue gases of a rotary kiln in a cement industry (CO2: 25 vol%) will be used for the production of value-added chemicals (acid additives for cement formulations) and materials (CaCO3 nanoparticles to be used as concrete fillers). A circular-economy-approach is enabled: the CO2 produced by cement manufacturing is re-used in a significant part within the plant itself to produce better cement-related products entailing less energy intensity and related CO2 emissions by a Quadratic effect.

Ionic liquids (bare or amine-functionalised) will be the key technological playground for the efficient and cost-effective (<30 €/ ton) purification of CO2 to a purity grade sufficient for the above mentioned utilisation paths. A dedicated pilot plant (flue gas flow rate: 50 Nm3/h) will be developed, based on the knowledge-based selection of the best ionic-liquids composition and operating conditions.

Within a final TRL 6 integrated system demo campaign, the thereby derived CO2 will be utilised in parallel to:

• promote the precipitation of nano-CaCO3 powders which act as strength enhancer and accelerator of the hydration rate.
• synthesize through electrocatalytic and catalytic pathways formic acid, oxalic acid and glycine to be used as hardening acceleration promoters, grinding aids or ionic liquids additives, respectively.

Distinctive features of the RECODE approach are the high process intensification and scale-up-ability; the use of low-grade heat sources; the meaningful reduction of CO2 emissions (>20% accounting for direct and indirect means) and the good market potential of their products at a mass production scale.

The first two years of the project will be focused on the development of key functional materials and process units at TRL 4-5, the third year on the assembly of single-process lines certified at TRL 5-6, and the testing at a cement manufacturing site (TITAN) of the TRL 6 integrated CO2 process.

RECODE proposes a new technology platform fully compliant with this mandate and capable of contributing for a >20% reduction of CO2 emissions in the medium to long term. This major impact will be achieved by:

1. CO2 capture, purification and conversion exploiting primarily REE which can be recovered from the waste heat (ORC)
2. Substitution of additives entailing strong CO2 generation in their current manufacturing routes (e.g. current FA production is generating 2.51 tons of CO2 per ton of FA according to the ECOINVENT database against the -0.96 tons of CO2 per ton of FA entailed by the adoption of only REE)
3. Generation of nanofillers (CaCO3) whose CO2 footprint is neutral (if marketed CaCl2 is used) or even carbon negative (if CaCl2 is prepared in house from CaO-containing rocks and HCl), as opposed to the current 0.21 tCO2/tCaCO3 footprint (ECOINVENT database). However, most of the benefit in this case in indirect since these fillers (as shown in section 1.4): i) allow adoption of SCM in the cement paste to a larger extent counterbalancing their hydration-hindering effect; ii) enable 10-40% increase the mechanical resistance of cement, thereby allowing a significant decrease of the cement used in concrete (5 wt% can be considered as a cautionary estimation).