Reactivation Properties of Carbide Slag as a CO₂ Sorbent During Calcination/Carbonation Cycles

The carbide slag from polyvinyl chloride production as industry hazardous wastes was proposed as CO₂ sorbent at high temperature in calcium looping cycle. The cyclic CO₂ capture behavior and the microstructure characteristics of the carbide slag as one of the typical calcium-based industrial wastes during the multiple calcination/carbonation cycles. Also, the comparisons between the carbide slag and the natural limestone in cyclic CO₂ capture behavior were made. XRD analysis demonstrates that the predominating constituent of the carbide slag is Ca(OH)₂. The carbonation temperature ranging from 650 to 700°C is favourable to cyclic carbonation of the carbide slag. The cyclic carbonation conversions of the carbide slag is lower than that of the limestone before a certain time, but the situation is converse after that time in a thermogravimetric analyzer. The carbide slag has better cyclic CO₂ capture capacity. The carbonation conversion of the carbide slag retains 0.28 after 100 calcination/carbonation cycles, while the two limestones achieve 0.08 and 0.14 respectively at the same reaction conditions in a dual fixed-bed reactor. The microstructure of the carbide slag by SEM reveals the reason why it possesses better CO₂ capture capacity.