CO2 capture performance of calcium-based sorbent doped with manganese salts during calcium looping cycle

The effects of manganese salts including Mn(NO(3))(2) and MnCO(3) on CO(2) capture performance of calcium-based sorbent during cyclic calcination/carbonation reactions were investigated. Mn(NO(3))(2) and MnCO(3) were added by wet impregnation method. The cyclic CO(2) capture capacities of Mn(NO(3))(2)-doped CaCO(3), MnCO(3)-doped CaCO(3) and original CaCO(3) were studied in a twin fixed-bed reactor and a thermo-gravimetric analyzer (TGA), respectively. The results show that the addition of manganese salts improves the cyclic carbonation conversions of CaCO(3) except the previous cycles. When the Mn/Ca molar ratios are 1/100 for Mn(NO(3))(2)-doped CaCO(3) and 1.5/100 for MnCO(3)-doped CaCO(3), the highest carbonation conversions are achieved respectively. The carbonation temperature of 700-720 degrees C is beneficial to CO(2) capture of Mn-doped CaCO(3). The residual carbonation conversions of Mn(NO(3))(2)-doped and MnCO(3)-doped CaCO(3) are 0.27 and 0.24 respectively after 100 cycles, compared with the conversion of 0.16 for original one after the same number of cycles. Compared with calcined original CaCO(3). better pore structure is kept for calcined Mn-doped CaCO(3) during calcium looping cycle. The pore volume of calcined MnCO(3)-doped CaCO(3) is 2.4 times as high as that of calcined original CaCO(3) after 20 cycles. The pores of calcined MnCO(3)-doped CaCO(3) in the pore size range of 27-142 nm are more abundant relative to clacined original one. That is why modification by manganese salts can improve cyclic CO(2) capture capacity of CaCO(3). (C) 2011 Elsevier Ltd. All rights reserved.