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

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 degrees 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 (similar to 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.

Automated summary

CuO Oxygen carrier (OC) and Ba/Sr sorbent supported by Mg-Al composites synthesized by mechanical mixing exhibited great reactivity and stability during the three-stage MSW syngas chemical looping combustion and HCl adsorption (CLCA) process. The Ba/Sr sorbent slightly influenced the redox ability of OC but had no impact on MSW syngas combustion, maintaining stability for 20 cycles. Higher H2O content and temperature facilitated sorbent regeneration for better HCl adsorption efficiency, and Ba-loading composite showed superior HCl adsorption performance due to its better regeneration efficiency. The migration of CuO/Cu to the surface enhanced stability in mechanical strength, elemental composition, and redox ability during long-term operation.