Core-shell Mg-MOF-74@Al2O3 catalyst for enhanced amine regeneration in CO2 Capture: Cooperative acid sites and solar-driven low-energy mechanism

• Developed a hierarchical inverted core–shell-like Mg-MOF-74@Al 2 O 3 catalyst for enhanced amine regeneration in CO 2 capture. • Established a metal-node–dependent benchmark M = Mg, Cu and Co identifying Mg as the most effective site. • Achieved 51.28% higher CO 2 desorption and 30.5% lower heat duty at 90 °C. • Identified stable cyclic performance (94.4% retention after 10 cycles) in catalyst reuse. • Revealed acid-base cooperative mechanism for accelerated carbamate decomposition, supporting the 54.64% efficiency boost. Carbon capture by amine absorption is widely deployed for CO 2 emission control, yet regeneration remains constrained by slow kinetics and high energy demand. Here we establish a metal-node–dependent benchmark for hierarchical inverted core–shell-like MOF-74@Al 2 O 3 solid-acid catalysts with M = Mg, Cu and Co, and identify Mg-MOF-74@Al 2 O 3 as the most effective catalyst for amine regeneration. The in situ–grown Mg-MOF-74@Al 2 O 3 features an intimate MOF-oxide interface, resulting from physical integration and structural–functional cooperation, which enables favorable microenvironmental conditions for the conversion of carbamate- and bicarbonate-derived species during stripping. At 90℃, Mg-MOF-74@Al 2 O 3 delivers the best overall stripping performance, increasing the total CO 2 desorbed by 51.28% while reducing the regeneration heat duty by 30.5% relative to an uncatalyzed baseline. Under identical conditions, Cu-MOF-74@Al 2 O 3 increases the total CO 2 desorbed by 39.56% with a 24.9% reduction in heat duty, whereas Co-MOF-74@Al 2 O 3 increases the total CO 2 desorbed by 31.50% with a 20.3% reduction. Mg-MOF-74@Al 2 O 3 retains 94.4% of its initial performance after 10 regeneration cycles, with the activity plateauing in subsequent cycles, demonstrating robust durability. These findings provide a clear metal-dependent benchmark for MOF-based solid-acid composites and offer a practical route to reduce the energy penalty of scalable amine-based CO 2 capture.