CO2 capture performance of synthetic sorbent prepared from carbide slag and aluminum nitrate hydrate by combustion synthesis

• Carbide slag as material is used to prepare CO2 sorbent by combustion synthesis.
• Glycerol addition in preparation of synthetic sorbent improves its CO2 uptake.
• The feasible combustion synthesis temperature for sorbent preparation is 800 °C.
• Synthetic sorbent (mass ratio of CaO:Ca3Al2O6 = 73:27) shows higher CO2 uptake.
• Synthetic sorbent possesses much higher sintering resistance than carbide slag.

A new CO2 sorbent was prepared from carbide slag, aluminum nitrate hydrate and glycerol water solution by combustion synthesis method. The effects of the sorbent preparation conditions (glycerol addition, combustion synthesis temperature, ratio of carbide slag to aluminum nitrate hydrate) and carbonation/calcination conditions (temperature, atmosphere and time) on CO2 capture performance of the synthetic sorbent were investigated in the calcium looping cycles. The addition of glycerol during the sorbent preparation exhibits an improvement on the cyclic CO2 capture capacity. It was also found that the optimal combustion synthesis temperature for the synthetic sorbent was in the range of 750–800 °C. The synthetic sorbent contained the mass ratio of CaO derived from carbide slag to Al2O3 derived from aluminum nitrate hydrate = 90:10 exhibited higher CO2 capture capacity (0.38 g CO2/g sorbent after 50 cycles). X-ray diffraction analysis showed that the main compounds of the synthetic sorbent were CaO and Ca3Al2O6 by X-ray diffraction analysis. The synthetic sorbent showed higher CO2 capture capacity than the carbide slag under severe calcination conditions (950 °C, CO2) and at short carbonation time (<5 min). From the present investigation, it shows that a high active synthetic CO2 sorbent could be obtained using the carbide slag in the calcium looping technology.

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