[EN] Steam hydration has been proposed as a suitable technique for improving the performance of CaO as a regenerable sorbent in CO2 capture systems. New hydration experiments conducted in this study, confirm the reported improvements in the capacity of sorbents to carry CO2. An examination of the textural properties of the sorbent after hydration and mild calcination revealed a large increase in the area of reaction surface and the formation of a fraction of pores ≈20 nm diameter that enhance the CO2 carrying capacity and increase the carbonation reaction rate. However, these changes in textural properties also lead to lower values of crushing strength as measured in the reactivated particles. Experiments conducted with a high hydration level of the sorbent (Ca molar conversion to Ca(OH)2 of 0.6) in every cycle produced a sixfold increase in the sorbent residual CO2 carrying capacity. This improvement has been estimated to be achieved at the expense of a very large consumption of steam in the system (about 1.2 mol of steam per mol of captured CO2). The trade off between the improvements in CO2 capture capacity and steam consumption is experimentally investigated in this work, it being concluded that there is need to design a comprehensive sorbent reactivation test that takes into account all of the hydration reactivation process.

This work is partially supported by the European Commission under the 7th Framework Programme (CaOling project). I. Martínez thanks Diputación General de Aragón for the F.P.I. fellowship and MICINN for the F.P.U. fellowship.

Peer reviewed