Preparation, characterization of Ca/Al carbonate pellets with TiO2 binder and CO2 sorption at elevated-temperature conditions

•High-temperature CO2 capture using Ca–Al–CO3 and TiO2 based sorbent•TiO2 nanoparticle improves surface area of sorbent.•Six Ca / Ti pellets were prepared with Ca–Al–CO3/TiO2 weight ratio of 1–6:1.•Ca / Ti pellet exhibits better stability in reactor than CaO based sorbent.•A possible scheme is described for stability of sorbent after cycles.

High-temperature CO2 capture using a Ca/Al carbonate sorbent, made of Ca–Al–CO3 powder and a TiO2 binder, was studied. Calcium aluminates were synthesized by the coprecipitation of Ca2 +, Al3 +, and CO32 − under alkaline conditions. The results showed that TiO2 nanoparticles significantly improved surface area and cyclic stability of sorbents in thermogravimetric analysis (TGA) and reactor. Six types of Ca / Ti pellets were prepared, using a Ca–Al–CO3/TiO2 weight ratio of 1–6:1. These granules gave a very stable CO2 uptake, to 80% of their full capacity, for 10 cycles, compared to only 35% using Ca–Al–CO3. A possible reaction scheme for stabilizing the CaO microstructure for multi-cycle experiments is described.

Graphical abstractA synthetic Ca/Ti pellets was used to investigate CO2 sorption in a fixed-bed reactor. The maximum slope of the CO2 volume with time indicates the optimum conditions. Ca/Ti pellets were good CO2 sorbents at 600–750 °C. The sorption volume rapidly plateaued at about 80 min, at 600–700 °C, from which we concluded that 750 °C was an appropriate capture temperature.Figure optionsDownload full-size imageDownload as PowerPoint slide