Sintering inhibiting effect and enhanced CO2 capture stability of MgO or La2O3 on calcined dolomite

The beneficial effect of 20 %wt.MgO or 20 %wt.La2O3 additives on pre-calcined dolomite to improve the CO2 sorption capacity in the calcium looping cycle (CaL) was studied by TG/DTG/DSC techniques at carbonation temperatures of 600–700 ◦C under mild conditions (carbonation in 25 %CO2–N2 balance and calcination at 900 ◦C in pure N2). The doped pre-calcined dolomites were prepared by wet chemical mixing method, followed by air-calcination at 900 ◦C, and characterized by XRD, SEM-EDS, and N2-physisorption analysis. Doped calcined dolomite exhibited a noticeably reduction of CaO crystallite size and enhanced SBET. In La2O3-doped calcined dolomite the formation of La2O2CO3 after carbonation stage was clearly confirmed by DTG/XRD analysis. After 10th CaL cycles both doped calcined dolomites showed minor deactivation degree and higher cycling stability over 40th CaL cycles compared to undoped dolomite. Kinetics analysis by the classical grain model estimated the intrinsic specific rates (k) in the kinetic-controlled stage significantly higher for the MgO doped calcined dolo mite. Meanwhile the Arrhenius activation energy values of 18.1 and 24.6 kJ mol 1 and pre-exponential factors of 4.5⋅10 3 and 5.6⋅10 3 mol m2 s 1 for MgO and La2O3 additives, respectively, were lower compared to undoped calcined dolomite (Ea =35.1 kJ mol 1 and A =0.15⋅10 3 mol m2 s 1).