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

Abstract The beneficial effect of 20 %wt.MgO or 20 %wt.La 2 O 3 additives on pre-calcined dolomite to improve the CO 2 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 %CO 2 –N 2 balance and calcination at 900 °C in pure N 2 ). 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 N 2 -physisorption analysis. Doped calcined dolomite exhibited a noticeably reduction of CaO crystallite size and enhanced S BET . In La 2 O 3 -doped calcined dolomite the formation of La 2 O 2 CO 3 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 dolomite. 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 m −2 s −1 for MgO and La 2 O 3 additives, respectively, were lower compared to undoped calcined dolomite (E a = 35.1 kJ mol −1 and A = 0.15⋅10 −3 mol m −2 s −1 ). • MgO or La 2 O 3 addition to pre-calcined dolomite by wet chemical mixing method enhanced CO 2 capture performance over CaL cycles. • High sintering-resistant and stability of MgO or La 2 O 3 modified calcined dolomite was obtained. • La(OH) 3 was used as precursor of La 2 O 3 additive, which was able to capture extra CO 2 . • Multiple carbonation (at 600 and 700 °C)/calcination cycles under 25 % CO 2 atmosphere were conducted.