CO₂ Capture with Mg-, Al-, and Zr- Assisted CaO-Based Sorbents in the Calcium Looping Process Under Mild and Realistic Conditions

The calcium looping (CaL) process is a promising carbon capture technology for CO2 capture from point source emitters. A key challenge in the CaL process is the loss of sorbent capacity over successive capture-regeneration cycles due to sintering, which affects long-term stability. This study addresses this issue by a novel approach of incorporating MgO, Al2O3, and ZrO2 as promoters into calcium-based sorbents synthesized using the solution combustion synthesis (SCS) method. Sorbents were developed in mono-, bi-, and trimetallic configurations using soluble metal nitrates as precursors. Among the tested sorbents, Ca/(Zr–Al) demonstrated the highest CO2 uptake of 0.46 g of CO2/g of sorbent, while Ca/(Mg–Zr–Al) achieved 0.43 g of CO2/g of sorbent. Both configurations exhibited exceptional stability, maintaining over 90% of their initial capacity after 50 cycles at elevated temperatures. These results highlight the effectiveness of bi- and trimetallic sorbents in enhancing the performance and durability of the CaL process.