The Effect of Doping CeO_2 for CO_2 Capture of Calcium-Based Sorbent at High Temperature

摘要

The fossil fuel power plant has been regarded as the chief culprit for the increasingconcentration of CO_2 in our atmosphere. In order to avoid the harm done by the greenhouse effect, itbecomes emergency to capture the CO_2 from flue gas of power plant. However, the currentseparation methods could not be conducted until the high temperature flue gas is cooled below 100℃.With the advantages of wide sources, low cost, easy preparation and regeneration, CaO becomes thesuitable absorbent for CO_2 at high temperature.In this study, aiming at the sintering problem of CaO through multiple carbonation andcalcination, a kind of modified calcium-based absorbent was studied to capture CO_2 from flue gas athigh temperature by doping CeO_2. The TGA was used to estimate the adsorption capacity ofabsorbents with different doping ratios of CeO_2 at 700℃ in the 30vol% CO_2 atmosphere. Ca/Ce(8:2),with the largest surface area(50.90m~2/g), had the best performance in all doped absorbents. In thecarbonation/calcination cycling experiments, the adsorption capacity of Ca/Ce(8:2) only dropped alittle with the increase of cycle number and kept well cycling stability (86.1%) after 20 cycles. TheBET data, SEM and XRD images demonstrated that the appropriate doping ratio of CeO_2 couldstructure a strong framework to obstruct the contact between CaO particles. The mesoporous werekept in good condition and sintering was almost prevented after multiple cycles at high temperature.And the optimal calcination condition for Ca/Ce(8:2) was studied. Ca/Ce(8:2) would be ananticipated high temperature absorbent for capture CO_2.