Li/Na/K carbonate solar salts for enhanced and integrated carbon capture and utilization via reverse water gas shift (ICCU-RWGS)

This study introduces a novel ICCU-RWGS process using Li, Na, and K carbonates mixed with boric acid as dual functional materials, enhancing CO 2 capture and conversion without traditional CaO adsorbents. These molten salts, compatible with solar energy systems, enable efficient integration with CSP, storing heat from CO 2 capture for utilization. The addition of boric acid significantly boosts CO 2 uptake and conversion, achieving 2.0 mmol, 1.1 mmol, and 1.3 mmol CO 2 uptake with conversion of 51.1 %, 58.3 %, and 57.6 % over three cycles, respectively. A 10-cycle test confirmed stable performance, with conversion rates between 53.0 % and 58.7 %. Characterization techniques (XRD, SEM, TEM, XPS, in-situ DRIFTS) revealed new borate phases after CO 2 capture. TG-DSC analysis showed exothermic peaks during CO 2 capture and RWGS stages, indicating that molten salt has the potential to generate heat for CSP systems, thus offering efficient CO 2 conversion and sustainable energy recovery. • ICCU-RWGS with molten salts was demonstrated. • Boric acid combined with Li/Na/K carbonates as ICCU DFMs. • Stability was confirmed over 10 cycles with 53. 0 %-58.7 % CO 2 conversion. • XPS confirms the critical role of boric in ICCU.