Thermal behavior of Cu-Mg-Al-Ba/Sr bifunctional composites during chemical looping combustion and HCl adsorption of MSW syngas

Abstract Mg-Al-supported composites of CuO Oxygen carrier (OC) and Ba/Sr sorbent synthesized by mechanical mixing were used for three-stage process of MSW syngas chemical looping Combustion and HCl adsorption (CLCA). The syngas combustion and HCl adsorption efficiencies as well as thermal behavior of the composites were investigated. It was found that the composites exhibited great reactivity and stability during cyclic CLCA process. The Ba/Sr sorbent slightly influenced the redox ability of OC owing to the presence of Cu2MgO3, but exhibited no impact on the MSW syngas combustion, achieving nearly full combustion during 20 cycles. Regarding to the conditions for sorbent regeneration, higher H2O content and temperature facilitated sorbent regeneration, allowing better HCl adsorption at fuel reaction stage. The sorbent regeneration conditions were optimized at 60 vol% H2O and 900 °C. Ba-loading composite exhibited better HCl adsorption performance than the Sr-loading during 20 CLCA cycles maintaining 25–35 ppmv HCl in flue gas because of its better regeneration efficiency (∼95%). The CuO/Cu migration to the surface enhanced the stability on mechanical strength, elemental composition and redox ability without appearing significant agglomeration during 20 cycles, maintaining the stability in the reactivity with MSW syngas for long-term operation.