Porous apatites as novel high temperature sorbents for carbon dioxide

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2014-10, Vol.254, p.586-596
• Main Authors: Landi, Elena, Riccobelli, Sara, Sangiorgi, Nicola, Sanson, Alessandra, Doghieri, Ferruccio, Miccio, Francesco
• Format: Article
• Language: English
• Subjects: Apatite; CO2 capture; CO2 carrying capacity; Solid porous sorbent
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2014.05.070

[Display omitted] •Synthetic hydroxyapatite as potential new material for CO2 capture at temperature higher than that of CaO based sorbents.•No appreciable decay of the absorbing activity upon several cycles.•The temperature of pre-treatment of porous granules impacts on sorption capacity.•CO2 carrying capacity very close to theoretical limit of 2.6% by mass.•Lower heat for regeneration in comparison with CaCO3 sorbents. Synthetic hydroxy-apatite was tested as a potential new material for CO2 capture at high temperature, over the operation limit of CaO-based sorbents. Some porous granules of hydroxy-apatite were prepared ad hoc. They were shown to absorb CO2 upon dehydroxylation in the very high temperature range of 900–1200°C, resulting in A-type carbonated apatite. No appreciable decay of the absorbing capacity was observed with a higher number of absorbing–desorbing cycles, differently from what happens in a conventional chemical sorbent, e.g. calcined natural calcium carbonate. The CO2 carrying capacity was maximum at 1000–1100°C and very close to the theoretical limit of 2.6% by mass. The macro-granule porosity network appeared to be effective in making the sites available for CO2 capture. At first glance, the process appeared to be chemically controlled. The pre-treatment temperature of the porous granules also had an impact on the sorption capacity. As a first proof of concept, the results obtained by thermogravimetric analysis, and supported by FTIR and XRD analysis, were confirmed by tests carried out in a laboratory-scale reactor, operated as a fixed bed.