Recycling CO2from flue gas for CaCO3nanoparticles production as cement filler: A Life Cycle Assessment

CaCO3 nanoparticles as filler have received considerable attention for the mechanical improvement that they provide to cements. However, their life-cycle impact on the environment remains almost unexplored, even if the cement industry is considered one of the largest CO2 emitters. In this perspective, this research work assessed a novel method for using CO2 from cement flue gases to produce nanoCaCO3 as cement filler within the cradle to cradle thinking. For this purpose, two routes of CO2 capture were assessed followed by the study of the synthesis of CaCO3 through a mineral carbonation. Three scenarios for the synthesis of CaCO3 nanoparticles were assessed targeting the use of waste or by-products as raw materials and recirculation of them to reduce any kind of emission. The three scenarios were evaluated by means of the Life Cycle Assessment methodology. Once the best considered route for nanoCaCO3 production was determined, this research work examined the environmental effect of including 2 wt% of CaCO3 nanoparticles into the cement. Closing the loop follows a circular economy approach since the CO2 is captured within the same cement factory. The results were compared with conventional Portland cement. Regarding nanoCaCO3 results, the scenario with simultaneous production of NH4Cl, and using as calcium source CaCl2 deriving from the soda ash Solvay process, proved to be the best option. Moreover, when cement was filled with 2 wt% of this nanoCaCO3, the benefit in terms of emission reductions in the Climate Change category was higher than 60 % compared to the conventional Portland cement.This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under Grant Agreement No. 768583- RECODE project (Recycling carbon dioxide in the cement industry to produce added-value additives: a step towards a CO2 circular economy, https://www.recodeh2020.eu/). This paper reflects only the author's view and the content is the sole responsibility of the authors. The European Commission or its services cannot be held responsible for any use that may be made of the information it contains.Publicad

MnOx-CeO2 catalysts synthesized by solution combustion synthesis for the low-temperature NH3-SCR

MnOx-CeO2 catalysts with different compositions have been investigated as catalysts for low temperature SCR by preparing a series of samples by the Solution Combustion Synthesis (SCS) method. Variable amounts of two different organic fuels (glycine and citric acid) with respect to the stoichiometry of synthesis were investigated. The samples were characterized by XRD, BET, H2-TPR, XPS, FESEM and their catalytic activity tested for NOx abatement in the range of temperature of interest (120-350 °C). By varying the synthesis parameters it was possible to obtain catalysts different in terms of structure, morphology, specific surface area, Mn average oxidation state as well as superficial content of Mn, Ce and O atoms. These features were correlated with the resulting catalytic performances in the SCR reaction and compared to pure MnOx phases obtained through the same synthesis method. All the developed catalysts were considerably active in the temperature range investigated and could be considered suitable for the low-temperature SCR process. The sample with the higher content of manganese oxide obtained with glycine in below-stoichiometric amount showed the best performance in terms of NOx conversion and N2 yield, likely due to the high reducibility as well as the presence of Mn3O4 phase