Pellets of a novel, high temperature CO2 sorbent, made of
CaO-impregnated porous Y2O3, were prepared. Yttria pellets were
synthesized from a mixture of yttria powder and a softener. A combination
of ethylene glycol, used as a softener, and a casting method yielded
mechanically stable pellets after calcination at 800ºC. Treatment of the Y2O3 support at higher temperatures further increases the pellets strength. The
same effect of pellets strengthening was observed after yttria impregnation
with CaO. Sorption capacity of the pellets with CaO content of 9 wt. %,
measured at isothermal conditions of 740ºC, reaches 7.5 wt. % for shorter
recarbonation time of 20 min and 8.5 wt. % for a longer time of 1 hour.
In this respect, sorption properties of pelletized CaO/Y2O3 are similar to
those of powdered material. A distinctive feature of the pelletized CaO/Y2O3 sorbent pretreated at high temperatures is the increase in capacity during
the initial cycles.