In-situ XRD studies of dolomite based CO₂ sorbents

Calcined dolomite (a CaOMgO material derivative of the natural mineral dolomite) has the potential as a CO₂ sorbent working at high temperatures (500-650 °C) in processes like post combustion carbonate-looping, or in sorbent enhanced reactions such as sorbent-enhanced water-gas shift (SEWGS) or sorbent-enhanced reforming (SER). However, deactivation and performance loss is inevitable and much effort has been aimed towards understanding and improving solid sorbents for various applications. This work presents a study of deactivation trends of calcined dolomite and Zr-modified versions of calcined dolomite that appears to possess better cyclic properties at rapid sorption-desorption cycling (which is a likely conditions in a real process using a CFB reactor). Surface area measurements, thermogravimetric analyses (TGA), fixed bed reactor studies, in-situ XRD and in-situ IR methods carried out at 600ºC in a gas containing 1-2vol% steam in 10% CO₂ have been conducted to obtain fundamental information about the de-activation mechanisms taking place.